Abstract: Even though study of clinical prostate specimen has demonstrated that tumor invasion of nerves correlates with poor prognosis, only recently have neural contributions to prostate carcinogenesis been discovered. Sympathetic nerves densely innervate the prostate, and increased sympathetic activity, as occurs in many disease states, is associated with an increased risk of developing prostate cancer and an increase in prostate cancer-specific mortality. Previous studies in our lab have demonstrated that sympathetic denervation of the prostate inhibits the progression of premalignant prostatic intraepithelial neoplasia PIN, and that this phenotype is mediated by ?2 and ?3 adrenergic receptors (Adrb2 and Adrb3) expressed on stromal cells. Our preliminary results indicate that (1) stromal Adrb2 and Adrb3 knockout inhibits tumor angiogenesis, (2) endothelial-specific Adrb2 deletion inhibits prostate cancer progression, and (3) gene expression analysis in endothelial cells isolated from high grade PIN tumors reveals a change in metabolic program. The goal of this project is to elucidate the mechanisms by which the sympathetic nervous system regulates tumor vascular development, and to study the role of chronic sympathetic hyperactivity on promoting prostate cancer progression. In order to examine the mechanisms by which sympathetic signals mediate tumor angiogenesis, we will quantify angiogenic changes in orthotopic cancer and matrix transplantation assays in conditional Adrb2 knockout animals, as well as perform ex vivo and in vitro metabolic assays to characterize the metabolic changes that occur in endothelial cells within the tumor microenvironment. Furthermore, to assess whether manipulation of neural input to the prostate can regulate cancer progression, we will develop and employ optogenetics to regulate sympathetic activity to the prostate during early stage cancer and assess the effects of chronic stimulation and inhibition on carcinogenesis. Through these experiments we hope to gain a better understanding of how the sympathetic nervous system mediates prostate cancer progression, and identify novel targets for therapeutic intervention as well as develop innovative proof-of-concept tools to inform prognosis and treatment.